Device for supplying fluid under pressure to two reversible load elements

ABSTRACT

This application discloses a device for supplying pressurized fluid to two load elements such as hydraulic motors, comprises two first conduits each connected to one load element and to a source of pressurized fluid, and two second conduits each connected to one load element and to an exhaust reservoir, a first flow divider being disposed in the first conduits, characterized in that the load elements are reversible, the first and second conduits are respectively placed in communication with the fluid source and the exhaust reservoir or vice versa, and a second flow divider is disposed in the second conduits.

O United States Patent 1 [111 3,864,910 Mechin Feb. 11, 1975 DEVICE FORSUPPLYING FLUID UNDER [56] References Cited PRESSURE T0 TWO REVERSIBLELOAD UNITED STATES PATENTS ELEMENTS 2,365,095 12/ I944 Miller et al60/97 E UX [75] Inventor: Gerard II. Mchin,

Nameull'lel'laudoulm France Primary Examiner-Edgar W. Geoghegan 73Assignee; societe Anonyme podain, Le Attorney, Agent, orFirm-Fitzpatrick. Cella, Harper Plessis-Belleville, France Sumo [22]Filed: Sept. 10, I973 [57] ABSTRACT [2]] App]. No.: 395,445

This application dlscloses a devlce for supplying pres- RehmdApplication Data surized fluid to two load elements such as hydraulic[63] Continuation-impart of Ser. No. 256,324, May 24, motors, comprisestwo first conduits each connected I972, abandoned. to one load elementand to a source of pressurized fluid, and two second conduits eachconnected to one [30] Foreign Application Priority Data load element andto an exhaust reservoir, a first flow Nov. 17, 1972 France 72.40991divider being disposed in the first conduits, character ized in that theload elements are reversible, the first [52] U.S. Cl 60/420, 60/468,60/484, and Second Conduits are respectively placed in com- 60/494munication with the fluid source and the exhaust res- [51] Int. Cl. F15b11/22 ervoir or vice versa, and a Second fl divider is [58] Field ofSearch 60/97 F, 420, 468, 484, p s d in the nd conduits- 13 Claims, 5Drawing Figures PATENIEDFEBI I I975- SHEET 30F 4 N F N.

Eur

DEVICE FOR SUPPLYING FLUID UNDER PRESSURE TO TWO REVERSIBLE LOADELEMENTS This is a continuation-in-part of copending application Ser.No. 256,324, filed May 24, 1972 now abandoned.

The present invention relates to a device for supplying fluid underpressure to two reversible load elements. In the field of load elementssupplied with fluid under pressure, and particularly, but notexclusively, in the field of hydraulic jacks and motors, it is known touse circuits in which two load elements or groups of elements areconnected in parallel. It is also known how to maintain a given ratiobetween the supply rates to the elements or groups, by incorporating aflow divider in the respective supply conduits, for example.

Such supply circuits are highly satisfactory for irreversible elements.Until now, however, no satisfactory arrangements have been proposed forreversible elements. A' first aim of the present invention is thereforeto fulfill this requirement.

Occasionally it is advantageous to provide a parallel supply to theelements,'either without flow division or with flow division for aselected sense of operation of the load elements. It is thus convenientto be able to render the corresponding flow dividers operative orinoperative at will. Another aim of the invention is to propose anarrangement providing for such selection.

The presence of a flow divider in the supply conduits and another in theexhaust conduits may result not only in supply to the load elements in agiven ratio but also of an'unwanted restriction in the exhaust flows.The invention also proposes an arrangement with which this disadvantagecan be avoided.

Further, the invention proposes an advantageous construction for thedevice, more particularly in that it comprises a monobloc valve actuatedby the pressurized fluid.

The invention thus has for its object a device for supplying pressurizedfluid to two load elements such as hydraulic motors, comprising twofirst conduits each connected to one load element and to a source ofpressurized fluid, and two second conduits each connected to one loadelement and to an exhaust reservoir, a first flow divider being disposedin the first conduits, characterized in that the load elements arereversible, the first and second conduits are respectively placed incommunication with the fluid source and the exhaust reservoir or viceversa, and a second flow divider is disposed in the second conduits.

Advantageously, each first conduit is connected to a third conduitproviding a by-pass for the first flow divider associated with thatfirst conduit, each second conduit is connected to a fourth conduitproviding a by-pass for the second flow divider associated with thatsecond conduit, the by-passes are provided with position-controllingelements, being those of the two third and two fourth conduitsrespectively, and which are so coupled that the two correspondingconduits are always in the same position.

Further, in one preferred embodiment of the invention, the controlelements of the third conduits and the fourth conduits are respectivelyactuated by the pressure of the fluid in the second conduits downstreamof the second flow divider with respect to the load elements and by thepressure of the fluid in the first conduits downstream of the first flowdivider with respect to the load elements, so that the first andsecondconduits are respectively placed in communication with the fluid source,the free communication of the first and second conduits with the exhaustreservoir being assured by by-passing the first and second flow dividersrespectively.

According to a further embodiment of the' invention there are providedadditional advantages according to which there is obtained withcertitude, the bypass of the flow divider disposed in the deliveryconduits, whatever the instantaneous mode of use of the device, and, ofcourse, when it is desired to obtain the division of the flows in thesupply conduits of the two load elements.

This last mentioned embodiment comprises two reversible load elements, asource of pressurised fluid, an exhaust enclosure, two first conduits,two second conduits, each of said first and second conduits beingconnected, on the one hand to one of the load elements, on the otherhand, selectively, the first conduits to the source of fluid and to theexhaust enclosure and the second conduits to the exhaust enclosure andto the fluid source, respectively. A first flow divider is interposed inthe two first conduits, a second flow divider in the two secondconduits, and four first connecting conduits are connected on the onehand in shunt to the parts of the first conduits connected on eitherside of the first flow divider, to the first flow divider, and on theother hand together at a first common point. Two non-return valves areeach disposed respectively in one of the connecting conduits which areconnected to the parts of the first conduits connecting the two loadelements to the first flow divider. These two first nonreturn valvesallows the passage of the fluid through said parts of the first conduitstowards the first common point, and four second connecting conduits areconnected, on the one hand, in shunt to the parts of the second conduitsconnected on either side of the second flow divider to this second flowdivider on the other hand, together at a second common point, and, twosecond non-return valves are each disposed respectively in one of theconnecting conduits which are connected to the parts of the two conduitsconnecting the two load elements to the second flow divider, these twosecond non-return valves allowing the passage of the fluid through saidparts of said second conduits towards said second common point.

Each of the first conduits is advantageously connected to a thirdconduit, which constitutes a by-pass to the first flow divider for saidcorresponding first conduit, each of the second conduits is connected toa fourth conduit, which constitutes a by-pass of the second flow dividerof said second corresponding conduit, whilst the by-passes thusconstituted are provided with position selecting means.

The selecting members are constituted by a twoway distributor, which isinterposed concomitantly in the by-passes of the first and second flowdividers, whilst, in its first position, this distributor ensures thecontinuity at its level of the said by-passes and, in its secondposition, said distributor obturates, at its level, said bypasses.

In the above described embodiment, there is provided a variable flowpump connected by two main conduits to the first and second conduitsrespectively. As a function of the first position of the memberadjusting the flow of said pump, one of said main conduits thenconstitutes the source of pressurised fluid, or the exhaust enclosure,while the other of said conduits constitutes, complementarily, theexhaust enclosure or the source of pressurised fluid.

The invention will be better understood and secondary features and theiradvantages will emerge from the following description of a number ofembodiments of the invention.

The description and the accompanying drawings are given by way ofnon-limitative example.

Reference will be made to the accompanying drawings in which:

FIG. 1 is a schematic diagram of a supply device according to theinvention;

FIG. 2 is a plan view of a valve used in the device of FIG. 1;

FIG. 3 is a view of the valve of FIG. 2 in the direction of the arrow Fin that Figure;

FIG. 4 is a section on the line IV-IV of FIG. 3; and

FIG. 5 is a circuit diagram of a supply device forming a furtherembodiment of the invention.

The device shown in FIG. 1 comprises two reversible hydraulic motors 1and a source of pressurised fluid comprising a pump 2 connected by aconduit 3 to a fluid reservoir 4 providing an exhaust reservoir. Themotors I are connected in parallel by two first conduits 5, eachconnected to one of the two chambers of a motor and to a single conduit6, and by two second conduits 7, each connected to the other chamber ofthe corresponding motor and to another single conduit 8.

A three-position distributor 9 is linked to the conduits 6 and 8, to aconduit of the pump 2, and to a conduit 11 which returns fluid to thereservoir 4 through a biased discharge valve 12. The first position ofthe distributor 9 connects together conduits 6 and 10 and conduits 8 and11. The second position connects together conduits 6 and 11 and conduits8 and 10. The third position connects together conduits l0 and 11 andshuts off conduits 6 and 8 at the distributor.

A valve 13 is disposed in conduits 5 and 7 to connect conduits 6 and 8.It comprises a first flow divider 14 which connects the conduit 6 to thetwo conduits 5 and a second flow divider 15 which connects the conduit 8to the two conduits 7. A first position of each flow divider provides agiven ratio between the fluid flow rates in the two conduits 5 (or 7).In the second position third conduits l6 and fourth conduits 17 providebypasses for conduits 5 and 7 respectively.

The flow dividers 14, 15 comprise respective control elements coupled tothe pistons 18, 19 of jacks whose cylinders 20, 21 are linked toconduits 8, 6 by conduits 22, 23. The control elements are also coupledto pistons 18a, 19a of jacks whose cylinders 20a, 21a are linked to acommon conduit 26 to which is connected a two-position distributor 27.

The distributor 27 is also connected to a conduit 28 connected to theconduit 11 upstream of the valve 12, relative to the reservoir 4, and toa conduit 32 which returns fluid to the reservoir 4. In a firstposition, the distributor 27 connects conduits 26 and 32 and closesconduit 28 at the distributor. In its second position it connectsconduits 26 and 28 and closes conduit 32.

In the valve shown in FIGS. 2 to 4 are provided some of the elementsalready mentioned. The valve comprises a body 36 to which are coupledthe conduits 5,6,7,8, 24 and by means of respective couplings 5a,

6a, 7a, 8a, 24a and 25a. FIG. 4 shows the flowdivider 15 in section. Theidentical flow dividers 14, 15, are disposed inYthe valve body 36.

Regarding flow divider 15, the two conduits 7 are connected in parallelto conduit 8 in a manner known per se. A double piston-37 slides freelyin a housing 38 formed in the valve body 36 and defines a chamber 7d ateach end of this housing. A shaft 39 slides in a housing 40 in the valvebody 36 and has two shoulders 41 which can occupy two positions. In afirst position the shaft 39 assures communication between the upstreamportion 7a and the downstream portion 7b with respect to piston 37 ofeach conduit 7, through a calibrated orifice 7c and the passage 42formed between the end of the piston 37 and the valve body 36. In asecond position the shaft 39 assures communication of parts 7a and 7b ofthe conduits 7 by grooves 43 from which the shoulders 41 are in thisposition disengaged. The shaft 39 is coupled to pistons 19 and 19a whilea spring 44 is located between the shaft 39 and the valve body 36. Thisspring has an action opposite to those of the fluid contents ofcylinders 21 and 21a. The conduit 22 is formed in the valve body 36 andconnects the conduit 8 to cylinder 20 (not visible in FIG. 4 but similarto cylinder 21).

The supply device which has just been described operates as follows, theoperation being described by way of example with reference to a vehiclein which one motor 1 drives a left-hand set of wheels while the othermotor 1 drives a right-hand set.

With the distributor 9 in its first position, conduits 6 and 10 andconduit 8 and 11 are in communication. With the distributor 27 in itsfirst position, as shown in FIG. 1, the fluid contained in cylinders 20aand 21a is returned to the reservoir 4 via conduits 24, 25, 26 and 32and is not under pressure. The spring of the flow divider 14 pushes backthe corresponding shaft 39, since it exerts a greater force than thefluid in cylinder 20 which is that exhausted into conduit 8 by themotors 1. The spring 44 of flow-divider 15, however, exerts less forcethan the fluid in cylinder 21 which is the pressurised fluid fromconduits 6 and 23. The divider 15 is thus brought into its secondposition in which direct communication is established between parts 7aand 7b of conduits 7, without flow division, whereas the divider 14 isin its first position and divides the fluid flows in a known manner, aswill be outlined below. The two motors 1 are thus supplied by flows in agiven ratio, their exhaust being entirely free with no restriction atthe divider 15. The vehicle thus has a blocked differential which allowsfor either left and right wheels driven at the same speed with equalflows, or for left and right wheels driven at different speeds. Thefirst provides a forwarding driving force and the second a turningmechanism.

When the divider 15 is in its first or flow-dividing position as shownin FIG. 4, the fluid reaching conduit 8 also reaches conduits 7a. Thefluid in each conduit 7a pushes back the corresponding end of piston 37,which is thus held in equilibrium, and reaches conduits 7b through theorifices 7c and passages 42 which generally form restrictions. The flowthrough orifices causes a drop in load and thus a pressure drop betweenthe corresponding conduit 7a and the associated chamber 7d. Theresulting pressures on each side of the piston 37, in chambers 7d, causethe admission to conduits 7b of flows in a given ratio determined by theorifices 7c.

With the distributor 9 kept in its first position and the distributor 27in its second position, cylinders 20a and 21a are supplied via conduits24, 25, 26 and 28 with fluid at the pilot pressure which is thatmaintained in conduit 11 by biased valve 12. Whatever pressure subsistsin cylinders 20 and 21, the fluid forces on pistons 18a and 190 aregreater than the spring forces of the corresponding flow dividers 14 and15. Thus each flow divider is in its second position with no flowdivision. The motors 1 of the left hand and right hand wheels are thussupplied in parallel and exhaust in parallel without any intervention byflow dividers l4 and 15, which in this configuration are by-passed.

If the distributor 9 is now brought into its second position,pressurised fluid is supplied via conduit 8 and exhausted from motors 1via the conduit 6. The complete operation, already described in relationto the first position of distributor 9, will not be described again, butwith the distributor 27 in its first position, flow dividers l4 and arein the second and first positions respectively, with no flow division bydivider l4 and division by divider 15. This is evidently the positionrequired, since division of the exhausted fluid is to be avoided in allcases, with the attendant load drop, whether the supply flows aredivided in a given ratio or not and whether the reversible motors 1 turnin one sense or the other.

There is thus obtained a hydraulic differential which can be locked butwhose operation involves only small load losses. The advantages of usinga monobloc for the valve 13 are well known, as are those of adoptinghydraulic control for the selection by distributor 27 of the mode ofoperation of the motors l.

The supply device shown FIG. 5 comprises two reversible hydraulic motors101 and a variable flow pump 102. The pump 102 is, for example,constituted as a pump with axial pistons and orientable plate, wellknown per se. It is connected to the rest of the device by two conduits102a and 102b which as a function of the position of the rod 102c forcontrolling the orientation of the swash plate of pump 102, constitute,one, the suction conduit, the other, the delivery conduit, and viceversa, of said pump.

Two flow dividers 103 and 104 are each shown diagramatically by tworestrictions and are in fact similar to the combination described in thefirst modification, with reference to FIG. 4, of the double actingpiston 37 mounted to slide in the housing 38 and making two passages 42,generally forming restrictions themselves.

The motors 101 are connected to pump 102 by two first conduits, each intwo parts 105a and 105b, and by two second conduits, each likewise intwo parts 106a and l06b. The two parts 105a of the first conduitsconnect one of the two connections of each motor 101 to the flow divider103, the two parts 10512 of these first conduits connecting said flowdivider 103 to the conduit 102a of the pump 102. Similarly, the twoparts 106a of the two conduits connect the other of the two connectionsof each motor 101 to the flow divider 104, the two parts 10612 of thesetwo conduits connecting said flow divider 104 to the conduit 10211 ofthe pump 102.

In addition, it is noted that a two-position distributor 107 isinterposed in the conduits 105b and 106b, and that two third conduits108 connect conduits 105a to this distributor 107, in the same way asfourth conduits 109 connect conduits 106a to said distributor 107. In

its first position, the distributor107 places the third conduits 108 incommunication with the second parts b of the first conduits on the onehand, and the fourth conduits 109 with the second parts l06b of thesecond conduits, on the other hand. On the contrary, in its secondposition, the distributor 107 obturates at its level the third conduits108 and fourth conduits 109. In its two positions,-the distributor 107maintains in communication the two parts of each of the conduits l05band 10612, which are connected thereto.

Furthermore, it is noted that four connecting conduits 110,111 and 112,113 are connected in shunt, to each of the first parts 1050 of the firstconduits and to each of the second parts 10512 of said first conduits,respectively. These four connecting conduits are in addition connectedtogether by means of another conduit 114 forming a junction and commonpoint. Two nonreturn valves 115 are disposed in the connecting conduits110 and 111, so as to permit the passage of the fluid from the firstparts 105a of the two first conduits towards the conduit 114 formingcommon point I In the same way, four other connecting conduits 1'16, 117and 1 18, 119 are connected in shunt, to each of the first parts 106a ofthe two conduits and to each of the second parts 106b of said secondconduits respectively. These four connecting conduits are in additionconnected together by means of another conduit 120 forming a junctionand common point. Two non-return valves 121 are disposed in theconnecting conduits 116 and 117 so as to permit the passage of the fluidfrom the first parts 106a and the two second conduits towards theconduit 120 forming common point.

An auxiliary pump 122 is connected by a suction conduit 123 to a fluidtank 124. To its delivery conduit 125 are connected, in parallel, twoconduits 126, 127 respectively connected, furthermore, to the conduits102a and 10212 of the pump 102. A first non-return valve 128 is disposedin conduit 126 and a second nonreturn valve 129 is disposed in conduit127, and each allow passage of the fluid of the delivery conduit 125towards conduits 102a and 102b, respectively.

A conduit 130 is branched in shunt in known manner to the deliveryconduit 125 and is connected to the fluid reservoir 124. A calibrateddischarge valve 131 is disposed in this conduit 130.

Finally, a single acting jack 132 is coupled to the movable member ofthe distributor 107. The effect of the pressurisedfluid in the jack 132is antagonistic of that of a spring 133 which tends to return saidmovable member of the distributor 107 into its first position. A secondtwo-position distributor 134 which is, for example, manually controlled,is provided, to which are connected on the one hand a conduit 135connected to the delivery conduit 125, on the other hand a conduit 136connected to jack 132, and a conduit 137 connected to the fluidreservoir 124. In its first position, the distributor 134 obturates atits level the conduit 135 and places the conduits 136 and 137 incommunication, whilst, in its second position, this distributor 134obturates at its level the conduit 137 and places conduits 135 and 136in communication.

Of course, the supply device which has just been described may becompleted by additions known per se and with their functions. It is thuspossible, for example, and it is often in fact done, to provide an extrasupply of pressurized fluid to the motors 101. To this end, it issufficient to connect in shunt to conduits 105a and low pressure, almostzero, and to dispose in each of these four conduits a non-return valveallowing passage of the fluid of the source under low pressure towardsthe conduits 105a and 106a.

In addition, the device described comprises several variants among whichthe following two will be mentioned:

The pump 102, as such is connected to the rest of the device, in factmakes a closed circuit supply. Naturally, an equivalent of thisconnection, which remains in the domain provided by the presentinvention, consists in connecting said pump on the one hand to a fluidreservoir and on the other hand to a three-position reversingdistributor enabling the delivery conduit of said pump to be placed incommunication either with the first conduits 105a and 105b or with thesecond conduits 106a l06b of the motors 101. This latter connection issaid to be open circuit and is moreover known per se.

The other variant consists in coupling the movable member of thedistributor 107, not to a power-assisted control device but to anordinary device for manually controlling its position.

The advantages in adopting the device which has just been described willbe better seen on reading the following description of the functioningobtained.

lt is assumed that the control rod 102C of the pump 102 is disposed sothat the conduit 102a constitutes the delivery conduit, the conduit 102bconsequently constituting the suction conduit. Moreover, it is obviousthat the reverse configuration leads only to reversing the direction ofrotation of motors 101.

It is noted that disposing the distributor 134 in its first positionplaced conduits 136 and 137 in communication, and consequently placesjack 132 in communication with the reservoir 124. The action of thespring 133 is therefore preponderant and the distributor 107 ismaintained or returned to its first position, too. In this firstposition of the distributor 107, direct communications are establishedbetween the first parts 105a and second parts 10512 of the firstconduits by conduits 108, and in the same way between the first parts106a and second parts 106b of the second conduits by conduits 109. Theflow dividers 103 and 104 are thus bypassed by conduits 108 and 109.

When, on the contrary, the distributor 134 is disposed in its secondposition, the fluid delivered by the pump 122 reaches, via conduits 135and 136,jack 132 and has a preponderant effect over that of the spring133. The distributor 107 is then pushed back until it is disposed in itssecond position. In this position, the only communications which remainare those between the first parts 105a and second parts 105b of thefirst conduits and between the first parts 106a and second parts l06b ofthe second conduits by means of the flow dividers 103 and 104, andpossibly in one direction only, by connecting conduits 110, 1 11, 112,113 and 114 on the one hand, and 116, 117, 118, 119 and 120 on the otherhand, since the conduits 108 and 109 are now obturated. It is then saidthat the flow dividers are not bypassed, it being understood that theyare not done so by conduits 108 and 109.

Finally, by way of example and to specify the materiality of theapplication made of the supply device, it is indicated that the motors101 constitute the motors driving the right and left-hand wheels on thesame axle of avehicleysuch as a tractor. On the other hand, these motorswhich are generally sufficiently fed with pressurised .fluid toeffectively drive the vehicle, may sometimes, when said vehicle goesdown a slope, no longer be supplied in sufficient volume. Under theseconditions, the motors are in fact driven by the vehicle and thepressure in their inlet conduit drops and becomes practically zero.

The following four situations are thenstudied:

First situation: the motors 101 effectively drive the loads to whichthey are coupled, and the flow dividers 103 and 104 are by-passed;

Second situation; the motors 101 are driven by the loads to which theyare coupled, and the flow dividers 103 and 104 are by-passed;

Third situation: the motors 101 effectively drive the loads to whichthey are coupled, and the flow dividers 103 and 104 are not by-passed;

Fourth situation: the motors 101 are driven by the loads to which theyare coupled, and the flow dividers 103 and 104 are not by-passed.

Concerning the first and second situations, in which the motors 101drive the vehicle or are driven by the vehicle, the fluid passes freelybetween the conduits 105a and 105b on the one hand, 106a and l06b on theother hand, by means of conduits 108 and 109 respectively. Consequently,the supplies of the motors 101 by conduits 102a, 105b, 108 and 105a areeffected in parallel, in the same way as the motor exhausts are alsoeffected in parallel by conduits 106a, 109, 106b and 102b. This mode ofsupply and exhaust is commonplace and well known per se.

When the distributor 134 is then disposed in its second position, theconduits 108 and 109 are closed. The fluid delivered by pump 102 intoconduit 102a, then into conduits 10512 must obligatorily pass throughthe flow divider 103. In fact, the path through conduits 112, 113 and114 is obturated at the level of the nonreturn valves 115. Theretherefore remains only the path passing through the flow divider 103.The flows feeding the two motors 101 are in a fixed ratio, thiscorresponding to the blocking of the hydraulic differential. Thisblocking may be advantageous for moving over poor ground.

If one is in the third or fourth situation, the fluid delivered by themotors 101 in the conduits 106a may return directly to the conduit 102bby conduits 116, 117, the non-return valves 121 and the conduits 120,118, 119 and 106b, since the non-return valves 121 effectively allow thefluid to pass in this direction. In fact, it is noticed that theconduits 116, 117, 118, 119 and 120 and the non-return valves 121constitute a second bypass path of the flow divider 104, this path beingpermanently open, but only in the direction permitting the flow of thefluid from motors 101 by conduits 106a towards conduit 102b.

Consequently, even if the pressure of the fluid in the supply conduitsl05b 105a drops, the flow divider disposed in the delivery conduits106a-106b of the motors 101 is efficiently by-passed, contrary toexample, to what happened with the device shown in the modification ofFIG. 1. Naturally, it is understood that, in view of the symmetry of thedispositions relative to the supplies and exhausts of the motors 101,the functioning is conserved, except for the direction of rotation ofsaid motors, when it is the conduit 10212 which becomes the supplyconduit of the pump 102, and when the suc- ,tion conduit of said duit102a.

It is to be 'noted'in addition that the lack of fluid which may occur inthe supply conduit of the pump 102, conduit 102a in the present case,when the motors 101 are driven by the vehicle, may be compensated by theextra supply procured from pump 122, by means of the conduits 125 and126, through the non-return valve 128.

What is claimed is:

1. A device for supplying pressurized fluid to two load elements such ashydraulic motors, comprising two first conduits each connected to oneload element and to a source of pressurized fluid, and two secondconduits each connected to one load element and to an exhaust reservoir,a first flow divider being disposed in the first conduits, characterizedin that the load elements are reversible, the first and second conduitsare respectively placed in communication with the fluid source and theexhaust reservoir or vice versa, and a second flow divider is disposedin the second conduits, a third conduit connected to each first conduitand providing a by-pass for the first flow divider associated with thefirst conduits, a fourth conduit connected to each second conduit andproviding va by-pass for the second flow divider associated with thesecond conduits, said by-passes being provided with positioncontrollingelements and so coupled as to maintain the two corresponding conduits inthe same position, the control elements of the third and fourth conduitsbeing respectively actuated by the pressure of the fluid in the secondconduits downstream of the second flow divider with respect to the loadelements and by the pressure of the fluid in the first conduitsdownstream of the first flow divider with respect to the load elements,so that the first and second conduits are respectively placed incommunication with the fluid source, the free communication of the firstand second conduits with the exhaust reservoir being assured byby-passing the first and second flow dividers, respectively.

2. A device for supplying pressurized fluid to two load elements such ashydraulic motors, comprising two reversible load elements, a source ofpressurized fluid, an exhaust enclosure, two first conduits, two secondconduits, each of said first and second conduits being connected, on theone hand to one of the load elements, on the other hand, selectively,the first conduits to the source of fluid and to the exhaust enclosureand the second conduits to the exhaust enclosure and to the fluidsource, respectively, a first flow divider interposed in the two firstconduits, a second flow divider interposed in the two second conduits,four first connecting conduits which are connected on the one hand inshunt to the parts of the first conduits connected on either side of thefirst flow divider, to the first flow divider, on the other handtogether at a first common point, two first non-return valves which areeach disposed respectively in one of the connecting conduits which areconnected to the parts of the first conduits connecting the two loadelements to the first flow divider, these two first non-return valvesallowing the passage of the fluid of said parts of the first conduitstowards the first common point, four second connecting conduits whichare connected, on the one hand, in shunt to the parts of the secondconduits connected on either side of the second flow divider to thissecond flow divider on the other hand, together at a second pump is thenconstituted by concommon point, and, two second non-return valves Iwhich are each disposed respectively in one of the con- 'nectingconduits which are connected to the parts of the two conduits connectingthe two load elements to the second flow divider, these two secondnon-return valves allowing the passage of the fluid of said parts ofsaid second conduits towards said second common point.

3. A supply device as claimed in claim 2, characterized in that each ofthe first conduits is connected to a third conduit, which constitutes aby-pass of the first flow divider for said corresponding first conduits,in that each of the second conduits is connected to a fourth conduit,which constitutes a by-pass of the second flow divider for saidsecondcorresponding conduits, and in that the by-passes thus constituted areprovided with position selecting means.

4. A supply device as claimed in claim 3, characterized in that saidselecting members are constituted as a two-way distributor, which isinterposed concomitantly in the by-passes of the first and second flowdividers, whilst, in its first position, this distributor ensures thecontinuity of the said by-passes and, in its second position, saiddistributor obturates, said by-passes.

5. A supply device as claimed inclaim 2, characterized in that itcomprises a variable flow pump connected by two main conduits to thefirst and second conduits respectively and in that, as a functionof theposition of the member adjusting the flow of said pump, one of said mainconduits constitutes the source of pressurized fluid, or the exhaustenclosure, the other of said conduits constitutes complementarily theexhaust enclosure or the source of pressurized fluid.

6. A 'device for supplying pressurized hydraulic fluid to two loadelements such as hydraulic motors, comprising two first conduits eachconnected to a different load element and to a first single conduit andtwo second conduits each connected to a different load element and to asecond single conduit, a first flow divider having restrictive flowpaths capable of producing a selected appointment of flow from saidfirst single conduit to said first two conduits, said first flow dividerbeing switchable into and out of fluid communication with said firstsingle conduit and said first two conduits, a second flow divider havingrestrictive flow paths capable of producing a selected apportionment offlow from said second single conduit to said second two conduits, saidsecond flow divider being switchable into and out of fluid communicationwith said second single conduit and said second two conduits, adistributor arranged for connecting said first and second singleconduits to a source of pressure and to a reservoir respectively andvice versa, first control means responsive to application of pressurizedfluid to said first single conduit to prevent switching of said secondflow divider into communication with said second single conduit and withsaid second two conduits and second control means responsive toapplication of pressized fluid to said second single conduit to preventswitching of said first flow divider into communication with said firstsingle conduit and with said first two conduits.

7. A device according to claim 6 wherein said device further includes asecond distributor operable subject to the operation of said first andsecond control means to switch said first and second flow dividers intocommunication with their respective conduits.

8. A device according to claim 6 wherein said first and second flowdivider means include hydraulic valves and wherein said control meanscomprise pressure operated pilot systems connected to operate saidvalves in response to changes in pressure in said first and secondsingle conduits.

9. A device according to claim 8 wherein said device includes furtherpressure operated pilot systems connected to operate said valves, asecond distributor and means associated with said second distributor forsupplying different fluid pressures to said further pressure operatedpilot systems, said pilot systems and said means associated with saidsecond distributor being of a size to provide less valve operating forcethan said pressure operated pilot systems.

10. A device according to claim 6 wherein said first and second controlmeans comprise bypass lines bypassing said flow dividers and checkvalves in said bypass lines permitting free fluid flow in a directionaway from said load elements.

11. A device according to claim 10 wherein said first and second singleconduits are connected respectively to opposite terminals of areversible hydraulic pump.

12. A device according to claim 11 wherein said first and second singleconduits are further connected, via associated check valves, to areservoir, said check valves allowing free fluid flow in a directionaway from said reservoir and toward said hydraulic pump and said loadelements.

13. A device according to claim 12 wherein said device includes meansfor maintaining a continuous circulating flow of hydraulic fluid past ajunction at a given pressure, a fluid operated, pressure responsivepilot system for switching said first and second flow divider means anda second distributor switchable to connect said junction and saidreservoir alternately to said pilot system.

} UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo.3,864,9l0. Dated February 11, 1975 Inventor(s) Gerard H. Mechin It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 35, "allows" should read --allow-;

Column 7, line 15, after "distributor" insert Column 7, line 35,"placed" should read -places;

Column 10, line 42, "appointment" should read --apportionment- Signedand sealed this 22nd day of April 1975.

(SEAL) Attest: I

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officerand Trademarks

1. A device for supplying pressurized fluid to two load elements such ashydraulic motors, comprising two first conduits each connected to oneload element and to a source of pressurized fluid, and two secondconduits each connected to one load element and to an exhaust reservoir,a first flow divider being disposed in the first conduits, characterizedin that the load elements are reversible, the first and second conduitsare respectively placed in communication with the fluid source and theexhaust reservoir or vice versa, and a second flow divider is disposedin the second conduits, a third conduit connected to each first conduitand providing a by-pass for the first flow divider associated with thefirst conduits, a fourth conduit connected to each second conduit andproviding a by-pass for the second flow divider associated with thesecond conduits, said by-passes being provided with position-controllingelements and so coupled as to maintain the two corresponding conduits inthe same position, the control elements of the third and fourth conduitsbeing respectively actuated by the pressure of the fluid in the secondconduits downstream of the second flow divider with respect to the loadelements and by the pressure of the fluid in the first conduitsdownstream of the first flow divider with respect to the load elements,so that the first and second conduits are respectively placed incommunication with the fluid source, the free communication of the firstand second conduits with the exhaust reservoir being assured byby-passing the first and second flow dividers, respectively.
 2. A devicefor supplying pressurized fluid to two load elements such as hydraulicmotors, comprising two reversible load elements, a source of pressurizedfluid, an exhaust enclosure, two first conduits, two second conduits,each of said first and second conduits being connected, on the one handto one of the load elements, on the other hand, selectively, the firstconduits to the source of fluid and to the exhaust enclosure and thesecond conduits to the exhaust enclosure and to the fluid source,respectively, a first flow divider interposed in the two first conduits,a second flow diviDer interposed in the two second conduits, four firstconnecting conduits which are connected on the one hand in shunt to theparts of the first conduits connected on either side of the first flowdivider, to the first flow divider, on the other hand together at afirst common point, two first non-return valves which are each disposedrespectively in one of the connecting conduits which are connected tothe parts of the first conduits connecting the two load elements to thefirst flow divider, these two first non-return valves allowing thepassage of the fluid of said parts of the first conduits towards thefirst common point, four second connecting conduits which are connected,on the one hand, in shunt to the parts of the second conduits connectedon either side of the second flow divider to this second flow divider onthe other hand, together at a second common point, and, two secondnon-return valves which are each disposed respectively in one of theconnecting conduits which are connected to the parts of the two conduitsconnecting the two load elements to the second flow divider, these twosecond non-return valves allowing the passage of the fluid of said partsof said second conduits towards said second common point.
 3. A supplydevice as claimed in claim 2, characterized in that each of the firstconduits is connected to a third conduit, which constitutes a by-pass ofthe first flow divider for said corresponding first conduits, in thateach of the second conduits is connected to a fourth conduit, whichconstitutes a by-pass of the second flow divider for said secondcorresponding conduits, and in that the by-passes thus constituted areprovided with position selecting means.
 4. A supply device as claimed inclaim 3, characterized in that said selecting members are constituted asa two-way distributor, which is interposed concomitantly in theby-passes of the first and second flow dividers, whilst, in its firstposition, this distributor ensures the continuity of the said by-passesand, in its second position, said distributor obturates, said by-passes.5. A supply device as claimed in claim 2, characterized in that itcomprises a variable flow pump connected by two main conduits to thefirst and second conduits respectively and in that, as a function of theposition of the member adjusting the flow of said pump, one of said mainconduits constitutes the source of pressurized fluid, or the exhaustenclosure, the other of said conduits constitutes complementarily theexhaust enclosure or the source of pressurized fluid.
 6. A device forsupplying pressurized hydraulic fluid to two load elements such ashydraulic motors, comprising two first conduits each connected to adifferent load element and to a first single conduit and two secondconduits each connected to a different load element and to a secondsingle conduit, a first flow divider having restrictive flow pathscapable of producing a selected appointment of flow from said firstsingle conduit to said first two conduits, said first flow divider beingswitchable into and out of fluid communication with said first singleconduit and said first two conduits, a second flow divider havingrestrictive flow paths capable of producing a selected apportionment offlow from said second single conduit to said second two conduits, saidsecond flow divider being switchable into and out of fluid communicationwith said second single conduit and said second two conduits, adistributor arranged for connecting said first and second singleconduits to a source of pressure and to a reservoir respectively andvice versa, first control means responsive to application of pressurizedfluid to said first single conduit to prevent switching of said secondflow divider into communication with said second single conduit and withsaid second two conduits and second control means responsive toapplication of pressized fluid to said second single conduit to preventswitching of said first flow divider into communication witH said firstsingle conduit and with said first two conduits.
 7. A device accordingto claim 6 wherein said device further includes a second distributoroperable subject to the operation of said first and second control meansto switch said first and second flow dividers into communication withtheir respective conduits.
 8. A device according to claim 6 wherein saidfirst and second flow divider means include hydraulic valves and whereinsaid control means comprise pressure operated pilot systems connected tooperate said valves in response to changes in pressure in said first andsecond single conduits.
 9. A device according to claim 8 wherein saiddevice includes further pressure operated pilot systems connected tooperate said valves, a second distributor and means associated with saidsecond distributor for supplying different fluid pressures to saidfurther pressure operated pilot systems, said pilot systems and saidmeans associated with said second distributor being of a size to provideless valve operating force than said pressure operated pilot systems.10. A device according to claim 6 wherein said first and second controlmeans comprise bypass lines bypassing said flow dividers and checkvalves in said bypass lines permitting free fluid flow in a directionaway from said load elements.
 11. A device according to claim 10 whereinsaid first and second single conduits are connected respectively toopposite terminals of a reversible hydraulic pump.
 12. A deviceaccording to claim 11 wherein said first and second single conduits arefurther connected, via associated check valves, to a reservoir, saidcheck valves allowing free fluid flow in a direction away from saidreservoir and toward said hydraulic pump and said load elements.
 13. Adevice according to claim 12 wherein said device includes means formaintaining a continuous circulating flow of hydraulic fluid past ajunction at a given pressure, a fluid operated, pressure responsivepilot system for switching said first and second flow divider means anda second distributor switchable to connect said junction and saidreservoir alternately to said pilot system.